Three Dimensional Imaging of Veins

ABSTRACT

An apparatus and method for creating a three dimensional imaging system is disclosed. There is a first source of laser light and a second source of laser light having a wavelength different from the wavelength of the laser light of the first source. The laser light from the first and second sources are combined, and the combined laser light is transmitted to a scanner. The scanner further transmits the combined light to a surface to be imaged.

This is a continuation of U.S. patent application Ser. No. 14/712,113,filed on May 14, 2015, which is a continuation of U.S. patentapplication Ser. No. 14/276,139, filed on May 13, 2014, now issued asU.S. Pat. No. 9,042,966, which is a continuation of patent applicationSer. No. 13/135,591, filed on Jul. 8, 2011, now issued as U.S. Pat. No.8,818,493, which is a continuation of U.S. patent application Ser. No.11/823,862, filed Jun. 29, 2006, now issued as U.S. Pat. No. 7,983,738.U.S. patent application Ser. No. 11/823,862 claims priority on U.S.Provisional Patent App. Ser. No. 60/817,623, filed on Jun. 29, 2006, andU.S. Provisional Patent App. Ser. No. 60/757,704, entitled “Micro VeinEnhancer,” filed on Jan. 10, 2006, and is a continuation-in-part of U.S.patent application Ser. No. 11/478,322, filed on Jun. 29, 2006, nowissued as U.S. Pat. No. 8,478,386, All disclosures of these referencesare incorporated herein by reference.

SUMMARY OF THE INVENTION

A laser based imaging system that can image veins, arteries, or otherorgans containing blood, and can generate three dimensional imagesrepresentative thereof.

BACKGROUND OF THE INVENTION

It is known in the art to use an apparatus to enhance the visualappearance of the veins and arteries in a patient to facilitateinsertion of needles into those veins and arteries as well as othermedical practices that require the identification of vein and arterylocations. Such a system is described in U.S. Pat. Nos. 5,969,754 and6,556,858 incorporated herein by reference as well as publicationentitled “The Clinical Evaluation of Vein Contrast Enhancement.”Luminetx is currently marketing such a device under the name “VeinviewerImaging System” and information related thereto is available on theirwebsite, which is incorporated herein by reference.

The Luminetx Vein Contrast Enhancer (hereinafter referred to as LVCE)utilizes a light source for flooding the region to be enhanced with nearinfrared light generated by an array of LEDs. A CCD imager is then usedto capture an image of the infrared light reflected off the patient. Theresulting captured image is then projected by a visible light projectoronto the patient in a position closely aligned with the image capturesystem. The light source for flooding the region to be enhanced does notdeeply penetrate to into the patient, and therefore, only the veins onthe surface of the patient are imaged. Further, the image representativeof the veins which is rendered onto the patient is two dimensional anddoes not provide any depth information. Still further, there is nomethod using such technology to display blood flowing at a given depthin the patient.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a perspective view of the optical apparatus for the laserbased vein enhancer of the present invention.

FIG. 2 is a control block diagram of the controlling elements of theoptical apparatus of FIG. 1.

FIG. 3A is a side cutaway view of a patient's arm, illustrating theveins within the patient's arm.

FIG. 3B is a top view of the veins in the arm of the patient in FIG. 3A.

FIG. 3C is a side view of the veins in the arm of the patient in FIG.3A.

FIG. 4A is a side view of the veins in the arm of the patient in FIG.3A, showing the scan depth lines from N=1 through N=17.

FIG. 4B shows 17 images for N=1 through N=17 of the arm of the patientin FIG. 3A that are stored in the image memory of laser based veinenhancer of the present invention.

FIG. 5 is a flow chart illustrating an embodiment of the image formatterof the optical apparatus of FIG. 2.

FIG. 6 is a top view of the veins in the arm of the patient in FIG. 3A,utilizing different patterns to differentiate between the variousdifferent veins and arteries.

FIG. 7 is a flow chart of another embodiment of the image formatter ofthe optical apparatus of FIG. 2.

FIG. 8 is a flow chart of a third embodiment of the image formatter ofthe optical apparatus of FIG. 2.

FIG. 9 shows a top front perspective view of an embodiment of the imageformatter of the optical apparatus of FIG. 2.

FIG. 10 shows the projection plane of the laser eased vein enhancer ofthe present invention on a cross section of a patient's arm.

FIG. 11 is an illustration of how an embodiment of the laser based veinenhancer of the present invention accurately projects the correct veinsize regardless of the depth of the veins within the patient's arm.

DETAILED DESCRIPTION OF THE INVENTION

Preliminary application No. 60/757,704, incorporated herein byreference, described a miniature laser based system for imaging apatient's veins and arteries and then rendering them onto the surface ofthe patient's skin. Tests of such a system has shown that the laserbased imaging system can penetrate and image very deeply into thepatients body, and in some cases, such as the hand or arm, can imageentirely through the hand or arm. Further, it has been found that thedepth of penetration of the imaging is a function of the amount of laserpower applied. Using these principals, a three dimensional imagingsystem is now described.

FIG. 1. shows the optical apparatus for a laser based vein enhancer. Asingle colored laser 180, for example a 630 nm semiconductor red laser,is projected into combiner 181. A semiconductor laser 183 is alsoprojected into the combiner 181. Laser 183 may have a is wavelength from700 nm to 1000 nm, with a preferred wavelength of 740 nm. Anillustrative example of a semiconductor 740 nm laser is SatherLasertechnik's Fabry Perot Diode Laser 740 nm, 10 mw, model numberFP-0740-10. The combiner 181 outputs a combined laser beam 184 which isthe combination of the 630 nm red and the 740 nm laser beams. Combinersfor combining two lasers of different frequencies are well known in theart and will not be further described herein. The combined laser beam184 is positioned to hit off mirror 172 and then to hit the MEMS scanner173. The MEMS scanner moves in a raster pattern thereby causing thecombined laser beam to move along optical path 5 forming a rasterpattern at the field of view 4. A photodetector 182 which is responsiveto the 740 nm wavelength is provided and receives 740 nm light reflectedoff objects in the field of view. The photodetector 182 outputs ananalog signal representing the amount of 740 nm light received. Anillustrative example of a photodetector is Roithner Lasertechnik's modelnumber EPD-740-1.

FIG. 2 shows a control block diagram for controlling the elements inFIG. 1 to form a three dimensional imaging system. An electronic block192 for driving the MEMS driver and for sensing the position of theraster scanner is provided. This block 192 generates the signalsrequired to drive the MEMS scanner 173 in a raster pattern, and alsodetermines the exact instantaneous location of the MEMS scanner andcommunicates this information to an image memory array 191A-191N. Thiselectronic block 192 also generates output signals indicating the framecount and communicates such signals to image memory array 191A-191N,image formatter 300, image memory two 196, and laser intensity block301.

Assuming the frame rate is sixty frames per second, the frame count willcycle from one through sixty. The operation is as follows. The MEMSscanner 173 is driven in a raster pattern. The first full frame afterachieving a stable raster pattern will be identified as frame one by theframe counter. Thereafter each subsequent frame will increase the framecounter by one, up to sixty, and thereafter the frame counter will resetto one and then start the cycle again. Laser intensity block 301 drivesthe laser drivers 195 at a select one of sixty levels depending upon thecurrent frame counter level More particularly, the laser intensity block301 drives the laser drivers 195 in such a manner that the power outputfrom the 740 nm laser 183 linearly increases in sixty steps as the framecounter increments from one to sixty. During the first sixty frames ofoperation the laser drive 194 for the 630 nm laser 180 is turned off.The light from the 740 nm 183 is reflected off the patient and absorbedby the blood in the veins in a patient's body and the reflected light issensed and converted into an analog signal by 740 nm photo detector 182.The analog signal is then passed through an A/C converter 190 whichoutputs a digital representation to image memory 191A-191N, wherein inthis example A=1 and N=60. Image memory 191A-191N receives instantaneousposition information from the electronic block 192, and based upon suchinformation, the digital representation for each pixel is stored in amemory location corresponding to a particular pixel. This is repeatedfor each pixel within a frame. In this manner, each frame is stored inan associated image memory. Upon completion of the first sixty frames,the image memory 191A-191N contains sixty images of the veins within thefield of view of the 740 nm laser 183, wherein each sequential imagememory contains an image which has been obtained with increased laserintensity. After the completion of the sixtieth frame, the image memoryis forwarded to an image formatter 300, which in tuna for is an imagewhich is transferred to image memory two 196. During each of the nextsixty frames of the cycle, the data in the image memory two 196 is readout as a function of the instantaneous position information provided bythe electronic block 192 and provided to a D/A converter 193 whichoutputs an analog signal to laser drive 194 which drives the 630 nmlaser 180. In this manner, the image that was stored in image memory two196 is projected by the 630 nm laser 180 onto the patient. In thismanner, the veins that are in the field of view become visible to thepractitioner.

While in the above embodiment, the frame count (number of slices ofimages taken) was sixty, the frame count could be more or less thansixty. Also, the laser intensity 301 was indicated to go up linearly. Itis also possible to have a look-up table or algorithm which provides fornon-linear step-ups in power. To simplify the discussion, the powerchanges have been described in a “step-up” fashion. The order in whichthe various steps are taken are unimportant, it is the capture of thevein signal at various intensities is what is important to the process.

The operation of image formatter 300 will now be described in greaterdetail. To simplify the Figs. shown, a maximum frame count of 17 (N=17)is illustrated as opposed to the frame rate of 60 (N=60) previouslydescribed. Accordingly, for the purpose of the illustrations the laserwill cycle through 17 frames at 7 different increasing power levels.Referring to FIG. 3A, a three dimension illustration of a patient's arm309 is shown. The arm has a top vein 310 which is closest to the topsurface and bottom vein 312 which is the deepest as viewed from the topsurface and middle vein 311 which is between the two. FIG. 3B shows atop view 308 of the veins 310, 311 and 312 as viewed from the top of thearm if the arm was transparent and the veins were not. FIG. 3C shows aside view 307 of the veins 310, 311 and 312 as viewed from the side ofthe arm (assuming again for the moment the arm is transparent and theveins are not).

The laser based vein enhancer of FIG. 1 and FIG. 2 is positioned so thatthe field of vie corresponds with the top view 308 of the patient's arm309 shown in FIG. 3. FIG. 4A again shows the side view 307 but alsoincludes along the right edge scan depth lines 314 N=1 through N=17.These scan depth lines 314 indicate how deeply the laser lightpenetrates info the arm at each respective laser intensity level N=1through N=17. FIG. 48 shows 17 images N=1 through N=17 that are storedin image memory 191A-191N. Referring to the image memory associated withframe one (N=1), the intensity of the laser only penetrates the patientarm to the depth shown by the N=1 scan depth line 314. Since this depthdoes not reach vein 310, 311 or 312 as shown in FIG. 4A, the imagestored for the first frame N=1 is blank. The same applies to the secondframe N=2. The third frame N=3 reaches partly into vein 310 andaccordingly the image stored in image memory associated with the thirdframe (where N=3) begins to faintly show vein 310. Frames 4, 5 and 6each penetrate successively deeper into vein 310 and therefore the imageof vein 310 gets successively darker in the image memory 191A-191Nassociated with frames 4, 5 and 6 (N=3, 4 and 5). Similarly, startingwith frame 7 (N=7), the middle vein 311 begins to appear and thenstarting with frame 11 (N=11) the deepest vein 312 begins to appear. Byframe 14 the laser light penetrates all the way through veins 310, 311,and 312 and therefore the images for frames 14 through frame 17 areapproximately the same and show all the veins.

If the image for frame 17 (N=17) ere to be projected onto the patientsarm, there would be no way for the practitioner to determine therelative depths of veins 310, 311 or 312. Accordingly the image needs tobe reformatted so as to provide additional information to thepractitioner before projecting on the patients arm.

Referring to FIG. 5, an illustrative embodiment of the image formatter300 of FIG. 2 is flow-charted. The frame counter N is set at 0 in step 2and all previously stored vein/artery images are cleared. In step 3 thecounter N is increased by one. In step 4 the frame counter is tested tosee if all 17 frames are completed. Accordingly, step 5 will be reachedfor each of the 17 successive images (N=1 through N=17). In step 5 theimage N is recalled from the appropriate image memory 191A-191N. In step6 all previously stored vein/artery pattern are subtracted. During thefirst frame N=1 there will be no previously stored vein/artery patternto be subtracted since they were cleared at step 2. At step 7, imageprocessing is performed to detect whether a vein or artery pattern isfound. Since it is know that veins and arteries are tube shaped and havea length much greater than their diameter, relative straightforwardcomputer processing can be used to identify such a pattern. If a newpattern is detected at step 8 the new vein/artery pattern is stored atstep 9 and the program returns to step 3. If there is no new patterndetected in step 8 the program returns to step 3.

Now applying step 1 through step 8 to the images shown in FIG. 4B,assuming that image N=3 represents the first time step 7 detects a vein310, the image of the vein 310 is stored at step 8. Thereafter, in eachsubsequent image processed, the image of vein 310 is removed from theimage at step 6. Then assuming when the N=7 the second vein 311 isdetected in step 9, the image of vein 311 is stored and accordinglyremoved the next time the program reaches step 6. Finally when the N=11the deepest vein 312 is detected in step 9, the image of vein 312 isstored and accordingly removed the next time the program reaches step 6.After completing the last frame 17, the program moves to Step 9 whereineach stored vein/artery pattern is replaced with a unique pattern. Forexample, the pattern of vein 310 can be replaced with a diagonallystriped pattern, the pattern of vein 311 can be replaced by a checkedpattern, and the pattern of vein 312 can be replaced with a light greypattern. A step 10 each of the now unique patterns for each at thestored vein/artery patterns are layered on top of each other, with thefirst found pattern falling on the top, the second pattern in the middleand the third pattern on the bottom. In step 11, the image of step 10 istransferred to image memory two 196 (See FIG. 2). The image of step 10is then projected by the visible laser onto the patients arm.

FIG. 6 shows the resulting image 320 projected onto the patients arm. Ascan be seen, vein 310 is represented by the diagonally striped pattern,vein 311 represented by the checked pattern, and vein 312 by a lightgrey pattern. It is clear to the practitioner that vein 310 ispositioned above veins 311 and 312 since the diagonally sniped patternat the intersection points of the respective veins. Similarly it isclear that vein 311 is positioned above vein 312 since the checkedpattern appears at the intersection point of veins 311 and 312.

In FIG. 6, diagonal striped patterns, checked pattern, and a light greypattern were utilized for differentiating between the various differentveins/arteries, however, the invention is not limited thereto. Varyingpatterns, such as dotted lines having different dot-spacecharacteristics could have been utilized to represent veins at differentdepths. Alternatively, solid images having different intensities couldhave been utilized, wherein, for example, those veins closer to thesurface are represented by dark projections and deeper veins by lighterprojections. Still further, the red laser 188 could be replaced bymultiple color lasers, for example red, green and blue, all arranged sothat their projections are aligned coaxially. By mixing the amount ofeach laser, color images can be projected. Accordingly, each differentdepth vein can be represented by a different color.

A further embodiment is shown with reference to FIG. 7. In thisembodiment, the capturing of the vein/artery image is the same as shownpreviously with reference to FIG. 2 and the resulting image gets storedin image memory 191A-191N. However, in this embodiment, the image is nottransmitted back onto the patient, but instead is transfer to a computer325 and is then displayed on a three dimension (3D) display 326. Morespecifically, three dimensional computer software is known in the art,such a CAD (computer aid design) software or medical imaging software,for manipulating and outputting 3D images. One example of such CADsoftware is SolidWorks. An example of medical imaging software is anAdvanced 3D Visualization and Volume Modeling software from Amira. SeeReal Technologies provides a stereo 3D display (Model C-s Display) whichreceives image information over a DVI connection from a graphics card ofa Windows based computer and allows the user to view such 3D imagewithout necessitating special glasses. Such Windows based computer mustbe fitted with a special graphics card, such as NVidea Open GL Videocard, to enable the driving of the display.

Utilizing the computer 325 and 3D display 326, the practitioner can viewthe veins in 3 dimensions. The 3 dimensional images can be rotated bythe CAD software, and cross-section slices of the 3 dimensional imagescan be performed. Still further, it is passible to utilize a 2dimensional display with CAD so ware converting the 3D image intomeaningful 2D displays.

FIG. 8 shows a still further embodiment wherein the visible laserprojection onto the patient of FIG. 2 is combined with the 3D display326 described with reference to FIG. 7. In this case, the image isprojected onto the patient by the 630 nm laser 180 while cogently beingdisplayed in 3D on screen 326. In this manner the practitioner can findthe exact positioning of the veins as projected on the patient and canalso view a 3D representation of the veins/arteries under the surface.

FIG. 9 shows an embodiment similar to that shown in FIG. 15A ofpreliminary application No. 60/757,704.

In this embodiment the Miniature Vein Enhancer (MVE) 150 includes asmall display 325, having attached thereto an attachment piece 154 and aMiniature Projection Head (MPH) 2. Although the attachment is shown at aright angle to the stem extending vertically from the vial, the stem canbe at an angle to the vial and the display angle can vary, as well. Aneedle protector 156, connects to a vial holder 7. The attachment piece154 receives the top of the needle protector and temporarily looks theMVE to the needle protector 156 which in turn attaches to the vialholder 7. The MPH 2 is attached to the small display 151 and is orientedso that the optical path 5 is such that the field of view 4 covers thepoint of the needle 14. The MPH 2 outputs the image of the veins 11 ontothe field of view 4 on the patient (not shown). The MPH 2 also providesthe image signal to the display 151 to be viewed on the display 151. Theimage signal includes both the veins and the needle 14. The display 151includes image processing capabilities that detects the position of thetip of the needle and displays a predetermined number of pixels of theimage around the tip of the needle on the display. In FIG. 14C, both theimage of the needle 153 and the image of the vein 152 are shown.

The unit of FIG. 9 is driven by the electronics (not shown) describepreviously in FIG. 8, wherein the computer 325, including the graphicscard and 3D software, are miniaturized and housed in the MVE 150 andwherein the display is a small 3D display 326 attached to the MVE 150.Accordingly, when this device is used, the practioner can view theprojected image on patient, as well as the three dimensional image onthe 3D display 326.

With reference to FIG. 10, a correction methodology is now described.The projection/imaging optical cone 445 of the MVE unit originates atthe mirror of the MVE and diverges from there. The projection angle, forexample, could be 60 degrees. A cross section of a patient's arm 446 isshown with a cross section of a first vein 443 shown at a first imagingplane 441 and a cross section of a second vein 444 shown at a secondimaging plane 441. A projection plan 440 is, also shown, which isapproximately on the top surface of the arm 446 of the patient andrepresents where the image is displayed on the patient. In this example,the first imaging plane 441 is half way between the projection plane 440and the second imaging plane 442. Due to the projection angle, thesecond imaging plane 442 is wider than the first imaging plane 441 whichin turn is wider than the projection plane 440. In this example, thefirst vein and the second vein are each the same size. The first vein443 as viewed at the first imaging plane 441 is one quarter the width ofthe first image plane 441. The second vein 444 as viewed at the secondimaging plane 442 is one sixth the width of the second image plane 442.Accordingly, when the images of the first and second veins are projectedon the arm 446 on projection plane 440, the first vein 443 will appearto be one quarter the width of the projection plane 440, and the secondvein 444 will appear to be one sixth the width of the projection plane440. It should be noted that neither the projected image of the firstvein 443 nor the projected image of the second vein 444 is accuratelyrepresentative of the actual vein size.

In accordance with the present invention, a sealing process can beperformed prior to transmitting the image of the veins onto theprojection image plane 440. As previously described, the laser power ofthe 740 nm laser can be sequentially increased for each frame. A depthtable correlating the depth of penetration of the 740 nm laser as afunction of laser power can be pre-stored in memory. This depthinformation can then be used to correct the actual image size of theveins 443 and 444 prior to projecting their images onto projection plane440. The correction algorithm can be straight forward trigonometry andtherefore is not described herein.

FIG. 11 describes an embodiment which accurately projects the correctvein size regardless of the depth of the veins 443 and 444 within thepatients arm. The optical path diverges at an angle 447 and hits aparabolic mirror 448 which is arranged to have a shape so that theoptical beam 449 exiting off the mirror 448 is parallel and does notdiverge. In this manner, the image of the veins 443 and 444 are both thesame size, and when they are projected onto projection plane 440, thesize of the vein images exactly matches that of the actual veins. As analternative embodiment, a lens could be used instead of a parabolicmirror 448 for converting the diverging optical path to a parallel path.

As yet a father embodiment, it has been determined that increasing thewavelength of the laser light emitted from the laser 183 increases thedepth of penetration into the flesh of the patient. This effect can beused to construct three dimensional images by increasing the wavelengthof laser light emitted on sequential frames, thereby allowing the systemto determine the depth of the veins (this is similar to the previousembodiment where the laser intensity was increased to obtain greaterpenetrations).

It should be noted that all embodiments herein have been described witha 740 nm laser 183 for imaging the veins/arteries. However, a broaderrange of wavelengths (700 nm to 1000 nm) could be utilized. Similarly,in the event a broader range of wavelengths are emitted by laser 183,the 740 nm photo detector 182 could be changed to a different wavelengthto receive the associated wavelength (700 nm-1000 nm). Still further,the 630 nm (red) laser 180 has been utilized for displaying the image ona patient. The 530 nm (red) laser 180 could be replaced with any visiblelaser (generally in the range of 400 nm-700 nm). Still further, thesingle (red) laser 180 could be replaced with multiple lasers configuredso that they project coaxially. For example, if red, green and bluelasers are utilized, full color images can be rendered.

It also should be noted that often description is made of identifyingvein, and in some cases veins and/or arteries. The invention not limitedthereto. Any portion of the body containing blood would be appropriatelyimaged by the devices of this invention.

What is claimed is:
 1. A three-dimensional vein imaging systemcomprising: means for emitting a beam of light comprising a firstwavelength of light and a second wavelength of light; a scannerconfigured to scan said beam of light onto a surface; means forincreasing an intensity of said emitted first wavelength of light in aplurality (n) of stepped intensity increases; a photodetector responsiveto said first wavelength of light, and configured to receive arespective plurality (a) of contrasted vein images formed bydifferential absorption and reflection of said first wavelength of lightfrom a plurality of increased depths respectively corresponding to saidstepped intensity increases, and further configured to convert each ofsaid plurality (n) of contrasted vein images into a respective signal;an image processor configured to receive said plurality of respectivesignals of said converted plurality of vein images, and to layer emswithin each of said plurality (n) of vein images in a processed veinimage, with veins being at a greater depth being processed to visuallyappear beneath veins at a shallower depth, said image processorconfigured to transmit said processed vein image to said second laser;and wherein said second laser and said means for scanning are configuredto project said processed vein image onto the surface.
 2. Thethree-dimensional imaging system according to claim 1 further comprisinga combiner configured to combine said laser light from said first andsecond lasers into a single coaxial beam of light.
 3. Thethree-dimensional imaging system according to claim 2 further comprisinga mirror configured to reflect said single coaxial beam of light to saidscanner.
 4. The three-dimensional vein imaging system according to claim3, wherein said scanner is configured to scan said single coaxial beamof light in a raster pattern.
 5. The three-dimensional imaging systemaccording to claim 1 wherein said image processor is further configuredto replace each of said visually layered veins in said processed veinimage with a unique graphical representation, for said projection ontothe surface by said second laser and said means for scanning.
 6. Thethree-dimensional imaging system according to claim 5 wherein each saidunique graphical representation comprises a unique pattern; and whereineach sari unique pattern is from the group of patterns consisting of: adot pattern a striped pattern, and a checkered pattern.
 7. Thethree-dimensional imaging system according to claim 5 wherein each saidunique graphical representation comprises a solid image with a uniquelydifferent intensity for each of said visually layered veins; and whereinsaid uniquely different intensity is progressively darker for veinslayered at successively shallower depths.
 8. The three-dimensionalimaging system according to claim 5 wherein said second laser is furtherconfigured to emit light at a plurality of other visible wavelengthsdifferent from said second wavelength; and wherein said unique graphicalrepresentation comprises projection by said second laser of a respectiveone of said other visible wavelengths for each of said visually layeredveins, with veins and vein portions at different relative depths beingrepresented by different colors.
 9. The three-dimensional imaging systemaccording to claim 1, wherein said first wavelength is in the range it700 nm to 1000 nm; and wherein said second wavelength is a visible redwavelength of light.
 10. The three-dimensional imaging system accordingto claim 1, wherein said plurality (n) of stepped intensity increasescomprise non-linear stepped intensity increases.
 11. Thethree-dimensional imaging system according to claim 1, wherein saidplurality (n) of stepped intensity increases comprise regularincremental stepped increases.
 12. A three-dimensional vein imagingsystem comprising: a first laser configured to emit a beam of light at afirst wavelength; a second laser configured to emit a beam of light at asecond wavelength, being different than said first wavelength; a scannerconfigured to scan said beams of light from said first and second lasersonto a skin surface; means for increasing an intensity of said emittedfirst wavelength of light in a plurality (n) of stepped intensityincreases; a photodetector responsive to said first wavelength of light,and configured to receive a respective plurality (n) of contrasted veinimages formed by differential absorption and reflection of said firstwavelength of light at from a plurality of incremental depthsrespectively corresponding to said incremental intensity increases, andfurther configured to output each said plurality of contrasted veinimages as a respective analog signal; an analog-to-digital converterconfigured to receive and to successively convert each said respectiveanalog signal of said plurality of vein images into a correspondingplurality (n) of digital vein images; a first memory configured tosequentially receive and store each of said corresponding plurality ofdigital vein images; an image processor configured to successivelyreceive each of said plurality (n) of digital vein images, and to layerveins within each of said plurality of vein images to create a processedvein image, with portions of veins being at a greater depth beingremoved to visually appear beneath overlying vein portions that are at ashallower depth, to indicate a relative depth of the veins; a secondmemory configured to receive and store said processed vein image; adigital-to-analog converter configured to receive and to convert saidprocessed vein image into an analog signal, and to output said analogsignal of said processed image to said second laser; and wherein saidscanner and said second laser are further configured to use said outputanalog signal of said processed image to scan said processed image ontothe skin surface with said second wavelength of light.
 13. Thethree-dimensional imaging system according to claim 12 furthercomprising: a combiner configured to combine said laser light from saidfirst and second lasers into a single coaxial beam of light; a mirrorconfigured to reflect said single coaxial beam of light to said scanner;and wherein said scanner is configured to scan said single coaxial beamof light in a raster pattern.
 14. The three-dimensional imaging systemaccording to claim 12 wherein said image processor is fluffierconfigured to replace each of said visually Layered veins in saidprocessed vein image with a unique graphical representation, for saidprojection onto the surface b said second laser and said means forscanning.
 15. The three-dimensional imaging system according to claim 14wherein each said unique graphical representation comprises a uniquepattern; and wherein each said unique pattern is from the group ofpatterns consisting of: a dot pattern, a striped pattern, and acheckered pattern.
 16. The three-dimensional imaging system according toclaim 14 wherein each said unique graphical representation comprises asolid image with a uniquely different intensity for each of saidvisually layered wins; and wherein said uniquely different intensity isprogressively darker for veins layered at successively shallower depths.17. The three-dimensional imaging system according to claim 14 whereinsaid second laser is farther configured to emit light at a plurality ofother visible wavelengths different from said second wavelength; andwherein said unique graphical representation comprises projection bysaid second laser of a respective one of said other visible wavelengthsfor each of said visually layered veins, with veins and vein portions atdifferent relative depths being represented by different colors.
 18. Thethree-dimensional imaging system according to claim 12, wherein saidfirst wavelength is in the range of 700 nm to 1000 nm; and wherein saidsecond wavelength is a visible red wavelength of light.
 19. Thethree-dimensional imaging system according to claim 12, wherein saidplurality tin) of stepped intensity increases comprise non-linearstepped intensity increases.
 20. The three-dimensional imaging systemaccording to claim 12, wherein said plurality (n) of stepped intensityincreases comprise regular incremental stepped increases.